Most cells including normal tissue derived primary cells are anchorage-dependent, and require a solid surface in order to proliferate, metabolize nutrients and produce biomolecules. Conventional means for growth of these cells on a small scale include petri-dishes, flasks and roller bottles. A number of approaches have been taken by various investigators to develop cell reactors with large surface-area-to-volume ratios for space and operational economy. Such devices include polymer sponge materices, multiple tubing, stacked-plate systems, coiled plastic sheets, microcarrier suspension culture and hollow-fibers. Another approach is to culture cells on a packing material inside a column shaped vessel. One of these systems uses glass beads designed for large scale cell cultivation. Another packing material has a "saddle" shape.
The packing substratum must have several properties:
i. To enable the attached cells to spread to their optimal size and shape in order to metabolize and proliferate; PA0 ii. To promote exchange of metabolites between the cells and the culture medium, by providing an increased ratio of surface to volume inside the packed vessel; PA0 iii. To facilitate medium flow to the cells by providing an increased ratio of surface to volume inside the packed vessel; PA0 iv. To maintain high cell density for long periods, for the production of various biomolecules, even in serum free media.